Reply To: Likin it so far…….Brocock Compatto .22

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DrPutz
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I have 4 of these now (1 – 177, 2 – 22, 1 – 25) – yea went a bit (ok way) overboard on them, but they are an awesome rifle.  Only my 177 is the only one that has the slingshot hammer.  The 22’s were advertised as slingshot, but were not.  The 25 does not have the slingshot option.  I have been looking for a place to buy a slingshot hammer, but have not tried the AZ place yet.

I have found out some tricks to help tune them easy-peasy.  First, I run the hammer screw all the way back, so it protrudes just a tiny bit.  Then I install a 1.79″ (or shorter) long hammer spring.  These are 0.48″ diameter and are unloaded (short by about 1/8 to 3/16).  The factory spring is way pre-loaded, but easy to cock.  I adjust the power by adjusting the spring gauge – 0.053″ to 0.063″ wire diameter.  Currently with the shorter springs, my 22’s have a 0.057″ diameter spring and getting 40 shots at 25 fpe with 6% variation and 1.0 efficiency (no slingshot).  The 177 got 50 shots,17 fpe at 1.7 efficiency with the slingshot.  The 25 has a 0.063″ spring and is getting 25 shots at about 33 to 34 fpe at 1.3 efficiency.  Some folks argue to use a short hammer throw, but with a short strong spring, it would be too much cocking force if you don’t have a long enough throw.  Plus it makes for very easy tuning – I never adjust the hammer screw.

Some lessons learned after 2 tanks of air and countless pellets:

  1. Skip the regulator on the 22 and 25 Compatto’s.  The transfer hole is very long and small diameter (3.7 to 4mm for 22 and 25; 2.5 for 177).  This causes lots of pressure drop – resulting in lower velocity, lower fpe, and lower shot count.  I am experimenting with a regulator in the 177, but I opened the hole up to 3.7mm – max to not damage the barrel set screw.  Removing the tube is a bear as well.  With the long transfer tube, the shot curve is pretty flat anyway.  Good enough for hunting and silhouette.
  2. DO NOT USE Viton O-rings in colder climates – lost 30 fps after discovering this in my cellar tonight.  Attached is the o-ring chart, unfortunately the numbers do not line up to the exploded diagram, but I have some starting notes.
  3. Need to “crown” or counter sink the breach end of the barrel and polish.  The breach end if very sharp and WILL damage your pellets resulting in a loss of accuracy.  I hand loaded for a while, but I am practicing off-hand and found that I had issues (other than poor offhand skills) – turns out the pellets were getting damaged on insertion.
  4. Be EXTREMELY careful with the muzzle end.  I had two fall on each other and the “stripper” in the shroud bent, causing clipping. The stripper is very week and can be damaged easily. I have to make an improved version…
  5. Cold weather affects the trigger.  I had mine set perfectly in the warm basement.  When I went to shoot in the cellar, it got lighter and lighter, then self discharged.  I am not sure why, but looking into that presently.  I like a lighter trigger for off-hand, so this is next on the to do list.  The trigger is really only 1 stage, with just a ton of initial free play.
  6. Use a cleaning rod when replacing the breach oring.  I use a 22 cal cleaning rod to keep the replacement oring from going too far, then a small allen wrench to nudge the new oring in place.  After a few tries, I can do it real easy.
  7. The screws are all over-tightened, so be careful and plan to replace a few screws (like the top rail).
  8. Be cautious when tying a bottle to the fill – I had my fill port lock open.

These are certainty a fun gun to shoot.  I could shoot 135 shots off-hand after work tonight without killing my arms.  I am looking forward to the Gen 2 version of the Bantam, though the cheap prices of the Gen 1 Bantam are really tempting.